Intravascular blood pump with balloon

ABSTRACT

An intravascular blood pump ( 1 ) comprises a ring seal ( 10 ) that is configured to assume a collapsed configuration and an expanded configuration and configured to contact and seal against an inner wall of the patient&#39;s blood vessel when inserted therein in the expanded configuration. A support member ( 12; 13 ) is disposed inside the ring seal ( 10 ) in order to support the ring seal ( 10 ) from the inside, wherein the support member ( 12; 13 ) is configured to collapse at least partially when a predetermined pressure difference between a proximal area and a distal area of the blood vessel acting on the ring seal ( 10 ) is exceeded.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a United States National Stage filing under 35 U.S.C. § 371 of International Application No. PCT/EP2018/061350, filed May3, 2018, which claims priority to European Patent Application No.17169581.0, filed May 4, 2017. The contents of each of each of theforegoing applications are hereby incorporated by reference in theirentirety. International Application No. PCT/EP2018/061350 was publishedunder PCT Article 21(2) in English.

BACKGROUND

This invention relates to an intravascular blood pump for percutaneousinsertion into a patient's blood vessel. The blood pump may be a rightventricular assist device, i.e. a blood pump for supporting the functionof the right ventricle of a patient's heart.

Intravascular blood pumps are used to support the function of apatient's heart, either as a left ventricular assist device (LVAD) orright ventricular assist device (RVAD). An intravascular blood pumptypically comprises a catheter and a pumping device attached to thecatheter and is inserted into the patient's heart, e.g. through theaorta into the left ventricle or through the vena cava into the rightventricle. The catheter may have an elongate body with a proximalportion and a distal portion and may extend along a longitudinal axis,wherein the pumping device is attached to the catheter typically at thedistal portion remote from an operator, such as a surgeon.

A ventricular assist device may be used for treating dysfunction ordysplasia of a patient's heart, such as congenital heart defects. Forinstance, during the so-called Fontan procedure, a RVAD is inserted intothe patient's heart so as to divert the venous blood from the rightatrium to the pulmonary arteries, i.e. the non-functional rightventricle is bypassed by the RVAD. Another application for a RVAD is forpatients that suffer from failure of the right ventricle, which may becaused e.g. by a therapy that includes a LVAD. A RVAD may be applied inaddition to a LVAD in order to relieve the right ventricle from abnormalhigh pressures, such as up to 25 mmHg, and avoid failure of the rightventricle during treatment of the left ventricle. Normal healthy venousblood pressure may be in the range from about 3 to 5 mmHg.

When used as a RVAD, the pumping device is advanced towards one lobe ofthe lung through the pulmonary artery by means of the catheter. Sincethe outflow of the blood pump is directed to the lung, the pressuredifference generated by the blood pump is very crucial, in particularcompared to a LVAD, which pumps blood from the left ventricle into theaorta. High pressure may cause harm to the vessels of the lung. Anormal, healthy pressure in the pulmonary artery would be in the rangefrom about 10 to 25 mmHg, usually about 15 mmHg. A higher pressure inthe pulmonary artery, such as 30 to 40 mmHg, or even 70 mmHg up to 100mmHg, may be found in patients with heart diseases.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an intravascularblood pump for percutaneous insertion into a patient's blood vessel,which provides protection against a high pressure difference along theblood vessel.

This object is achieved according to the present invention by a bloodpump having the features of independent claim 1. Preferred embodimentsand further developments of the invention are specified in the claimsdependent thereon.

According to the invention, an intravascular blood pump for percutaneousinsertion into a patient's blood vessel is provided, which comprises acatheter, a pumping device and a ring seal with a support memberdisposed inside the ring seal. The pumping device comprises a blood flowinlet, a blood flow outlet and a rotor so as to cause blood to flow fromthe blood flow inlet to the blood flow outlet. The ring seal is disposedon the pumping device between the blood flow inlet and the blood flowoutlet.

The ring seal can assume a collapsed configuration and an expandedconfiguration and is configured to contact and seal against an innerwall of the patient's blood vessel when inserted therein in the expandedconfiguration. In this manner, the ring seal separates a proximal areaof the blood vessel from a distal area of the blood vessel. The supportmember is disposed inside the ring seal in order to support the ringseal from the inside, wherein the support member is configured tocollapse at least partially when a predetermined pressure differencebetween the proximal area and the distal area of the blood vessel actson the ring seal. At the same time, the support member is configured towithstand a pressure difference of up to 100 mmHg, preferably less, suchas up to 50 mmHg, preferably up to 20 mmHg. Throughout this disclosure,the term “distal” refers to directions away from a user and towards theheart, whereas the term “proximal” refers to directions towards a user.In other words, the ring seal collapses when the pressure differencethat is created by the blood pump between an inlet side and an outletside is greater than the predetermined value. Preferably, the blood pumpis configured to be inserted into a pulmonary artery.

The support member is particularly a mechanical support member asdescribed in more detail below. While the support member is configuredto keep the ring seal in the expanded configuration up to apredetermined pressure difference, it is at the same time flexibleenough to ensure that the predetermined pressure difference between theproximal and distal areas in the blood vessel is not exceeded. This isimportant to limit the pressure increase that is created for example bya blood pump in a pulmonary artery. The ring seal does not occlude theblood vessel at a pressure difference of 100 mmHg or more, preferably 20mmHg or more as described in more detail below. In other words, the ringseal acts like an overpressure valve, which means that blood is allowedto flow in a direction towards the lower pressure side past the ringseal once a predetermined threshold for the pressure difference isexceeded. The provision of the ring seal, thus, provides aself-regulating pressure in the blood vessel. An internal pressure ofthe ring seal is preferably atmospheric, i.e. the interior of the ringseal may be in fluid communication with the environment, e.g. by meansof an open line.

The ring seal, in particular its outer general shape independent of thecatheter body extending there through, may have any size and shapeappropriate for a desired application. For instance, the ring seal maybe spherical, ellipsoidal, cylindrical or a combination thereof. Thering seal may be symmetric, in particular axially symmetric, withrespect to a central longitudinal axis of the catheter, or asymmetric.An outer diameter of the ring seal, in particular in the expandedconfiguration, may be chosen dependent on the application. In oneembodiment, which may be suitable for an application in a pulmonaryartery, the outer diameter of the ring seal in the expandedconfiguration may be from about 1 cm to about 2.5 cm. The pumping devicemay have a length of about 3 to 6 cm.

Preferably, the support member is configured to withstand apredetermined pressure difference between the proximal area and distalarea of up to about 20 mmHg, which is an appropriate pressure differencefor an application in which the catheter is advanced into a pulmonaryartery. In other words, the support member is configured to maintain theexpanded configuration of the ring seal at a pressure difference betweenthe proximal area and distal area in the blood vessel up to 20 mmHg, andcollapses once the pressure difference exceeds 20 mmHg. Depending on adesired application, the predetermined pressure difference may be in therange from about 5 mmHg to about 35 mmHg, more preferably from about 7mmHg to about 30 mmHg.

In one embodiment, the ring seal comprises a flexible membrane. Inparticular, the membrane may be flexible and elastic. In this manner,the membrane is able to follow the expanded and collapsed configurationof the ring seal. The membrane may form a casing that encloses thesupport structure. In particular, the membrane may form a balloon havingan inflation port that allows fluid to be supplied to and to be removedfrom the balloon. The inflation port may be connected to a fluid lineextending along the elongate body of the catheter so as to allow toinflate the balloon by supplying fluid to the balloon and to deflate theballoon by removing fluid from the balloon. In particular, the fluidline may be a vacuum line in order to allow creating a vacuum ornegative pressure in the balloon to collapse the ring seal. The balloonand fluid line may be suitable for any fluid, such as liquids or gases,in particular saline or air. As mentioned above, the pressure in thering seal may be atmospheric pressure. Therefore, the fluid line that isconnected to the balloon may be open to the environment or otherwiseconfigured to level the pressure inside the balloon to atmosphericpressure.

The support member may be at least partially compressible. This allowsthe support member to stay inside the ring seal even in the collapsedconfiguration. Alternatively, or in addition, the support member may beretracted from the ring seal in order to bring the ring seal from theexpanded configuration to the collapsed configuration.

Preferably, the support member is biased to the expanded configuration.This provides the ring seal with self-expanding (or self-inflating) andself-holding characteristics. In other words, no external actuation isneeded to bring the ring seal from the collapsed configuration to theexpanded configuration because the ring seal tends to assume theexpanded configuration when no loads are applied. In particular, whilethe ring seal may be held in the collapsed configuration by applying avacuum, releasing the vacuum may cause the ring seal to expand. It willbe appreciated that, nevertheless, expansion of the ring seal might beenhanced by external actuation, e.g. by means of a pressurized fluidthat is supplied to the ring seal.

In one embodiment, the support member may comprise a foam or sponge. Thefoam may be a closed-cell foam or an open-cell foam. The foam can assumean expanded configuration e.g. at atmospheric pressure and may becompressed by applying a vacuum or other external force on the ringseal. In particular, if the foam is enclosed by a flexible membrane, thering seal comprising the foam and the membrane is particularly suitableto adapt to the size and shape of an inner vessel wall. Thecharacteristics of the foam may be chosen to allow the ring seal tocollapse at a predetermined minimum pressure. The foam may comprise anysuitable material, in particular a polymeric material, such aspolyurethane. The structure of the foam or sponge is chosen to set thepredetermined minimum pressure at which the ring seal shall collapse, orin other words to set a predetermined pressure difference up to whichthe support structure maintains the expanded configuration.

In another embodiment, the support member may comprise at least oneelastic wire, preferably made of a shape memory material, such asNitinol. Alternative materials that have shape memory characteristics orsuperelastic characteristics, such as nylon, can be used. Generally,shape memory is a temperature dependent property that allows the shapememory material the ability to undergo deformation at one temperatureand then recover its original, undeformed shape upon heating above its“transformation temperature”. The temperature change causes atransformation between the martensite phase and austenite phase of thematerial. Superelasticity is a temperature independent property thatallows the shape memory material the ability to undergo a mechanicaldeformation due to an external force applied to the shape memorymaterial, and then recover its original undeformed shape upon release ofthe external force. The superelasticity, which is also referred to aspseudoelasticity, is caused by a transformation between the martensitephase and the austenite phase that occurs due to external loads.

The wire, which may be made of Nitinol as mentioned above, can beretracted from the ring seal in order to be able to collapse the ringseal. Upon retraction of the wire, it can be straightened by pulling itinto a lumen of the catheter. Vice versa, when the wire is advanced intothe ring seal, it may assume a curved shape to thereby expand the ringseal. The curved shape may be a predetermined shape of the shape memorymaterial, and may be e.g. helical or otherwise shaped to provide adesired expanded configuration of the ring seal. In particular, the wiremay apply a force to the flexible membrane from the inside of the ringseal to expand the ring seal. In addition, although not necessary, thering seal may be filled with a fluid, such as a liquid or gas uponexpansion. Accordingly, the fluid may be removed from the ring seal uponretraction of the elastic wire from the ring seal.

In one embodiment, the ring seal may comprise a flexible shieldextending from an outer circumference of the ring seal, i.e. an outercircumferential surface of a body portion of the ring seal. The flexibleshield may be configured to contact the inner vessel wall when thecatheter is inserted in the blood vessel and the ring seal is in theexpanded configuration. The shield may be relatively soft and flimsycompared to the body portion of the ring seal, which may reduce the riskof causing harm to the blood vessel and may further improve adaptationof the ring seal to the size and shape of the blood vessel. The shieldmay be formed as a skirt or sleeve that surrounds the ring seal and issupported by the ring seal. The shield preferably collapses and expandsas the ring seal collapses. The shield may have a proximal end attachedto the ring seal and a free distal end configured to contact the innervessel wall. Thus, the shield may be open in a direction of the bloodflow in order to prevent a backflow and improve the sealingcharacteristics. However, since the shield collapses as the ring sealcollapses the pressure difference in the blood vessel is limited asdescribed above.

The shield may comprise a stiffening structure. The stiffening structuremay have at least one fluid receiving channel configured to be inflatedby receiving a fluid in order to stiffen the shield and to be deflatedby removing the fluid in order to soften the shield. For example, theshield may have longitudinally extending channels to form anumbrella-like shield. It will be appreciated that any other size, shape,number and configuration of the channels may be possible that issuitable to provide stiffness for the shield, e.g. helically curved. Thechannel or channels may be completely filled or emptied or onlypartially filled or emptied. This may allow to adjust the stiffness ofthe shield.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofpreferred embodiments, will be better understood when read inconjunction with the appended drawings. For the purpose of illustratingthe present disclosure, reference is made to the drawings. The scope ofthe disclosure is not limited, however, to the specific embodimentsdisclosed in the drawings. In the drawings:

FIG. 1 shows an intravascular blood pump inserted in a patient's heart.

FIG. 2 shows a cross-sectional schematic view of a ring seal of acatheter according to one embodiment in the expanded configuration.

FIG. 3 shows the ring seal of FIG. 2 in the collapsed configuration.

FIG. 4 shows a cross-sectional schematic view of a ring seal of acatheter according to another embodiment in the expanded configuration.

FIG. 5 shows the ring seal of FIG. 4 in the collapsed configuration.

FIGS. 6 a and 6 b show cross-sectional views of different examples of aring seal for the embodiment of FIG. 4 .

FIG. 7 shows a cross-sectional schematic view of a ring seal of acatheter according to yet another embodiment in the expandedconfiguration.

FIG. 8 shows the ring seal of FIG. 7 in the collapsed configuration.

DETAILED DESCRIPTION

In FIG. 1 is illustrated an intravascular blood pump 1 inserted into apatient's heart H. More specifically, in this illustrative embodiment,the blood pump 1 comprises a catheter 100 by means of which the bloodpump 1 is inserted into the pulmonary artery PA through the rightventricle RV of the patient's heart H via the inferior vena cava IVC. Ina different approach, the catheter may be inserted through the superiorvena cava SVC. During its operation, the blood pump 1, in particular thecatheter 100 extends through the tricuspid valve TRV and the pulmonaryvalve PV. The blood pump 1 comprises a pumping device 2 having a bloodflow inlet 3 and a blood flow outlet 4. An impeller or rotor (not shown)is provided to cause the blood to flow into the blood flow inlet 3towards and out of the blood flow outlet 4. The blood pump 1 accordingto this embodiment is designed as a right ventricular assist device(RVAD) and may be used e.g. in a Fontan procedure or in addition to aleft ventricular assist device (LVAD). The pumping device 2 is placed inthe pulmonary artery PA.

The blood pump 1, in particular the pumping device 2, is provided with aring seal 10. The ring seal 10, which is described in more detail belowwith reference to FIGS. 2-6 can assume an expanded configuration and acollapsed configuration and is shown in the expanded configuration inFIG. 1 . The ring seal 10 contacts the inner wall of the pulmonaryartery PA and, thus, seals a proximal portion of the pulmonary artery PAagainst a distal portion of the pulmonary artery PA. The operation ofthe blood pump 1 creates a pressure difference between the proximal anddistal portions of the pulmonary artery PA, more specifically a pressureincrease from the proximal portion towards the distal portion. In orderto limit the pressure increase, the ring seal 10 is configured tocollapse once a predetermined minimum pressure difference between theproximal and distal portions of the pulmonary artery PA is reached, i.e.the ring seal 10 withstands a pressure difference of up to apredetermined pressure difference. The ring seal 10 in the collapsedconfiguration allows blood to flow from the distal portion of thepulmonary artery PA towards the proximal portion of the pulmonary arteryPA past the pumping device 2. Once the pressure difference falls belowthe predetermined minimum pressure, the ring seal 10 may expand again.This is promoted by self-expansion properties of a support member insidethe ring seal 10 as will be described in more detail below. Thepredetermined minimum pressure difference may be about 20 mmHg for anapplication in the pulmonary artery PA.

Referring now to FIG. 2 , the ring seal 10 of the pumping device 2 isshown in a schematic longitudinal cross-sectional view inserted into ablood vessel V. It will be appreciated that details of the blood pump 1are omitted for the sake of simplicity. FIG. 2 shows the ring seal 10 inthe expanded configuration disposed about the pumping device 2. The ringseal 10 comprises a flexible membrane 11 that forms a balloon-likeelement. The flexible membrane 11 encloses a support member 12, whichcomprises a foam in this embodiment, in particular a polyurethane foam.The foam is biased to the expanded configuration to provideself-expanding and self-holding properties for the ring seal 10.Preferably, the interior of the ring seal 10 is under atmosphericpressure, when in the expanded configuration. A vacuum line 14 may beprovided to remove fluid, such as a liquid or gas, from the ring seal 10to bring the ring seal 10 actively into the collapsed configuration,e.g. during insertion of the pumping device 2 or for removal of thepumping device 2 from the patient's heart H.

The ring seal 10 is shown in the collapsed configuration in FIG. 3 . Inthe collapsed configuration, the foam is at least partially compressed.This may be achieved by removing fluid from the ring seal 10. Inparticular, however, the ring seal 10 collapses automatically when apredetermined pressure difference between opposing sides that acts onthe ring seal 10 is exceeded. The minimum pressure difference may bebetween 7 mmHg and 30 mmHg, and may preferably be 20 mmHg. The directionof the pressure difference between a higher pressure and a lowerpressure is indicated at arrow P in FIG. 2 .

Another embodiment is shown in FIG. 4 , which is similar to theembodiment of FIGS. 2 and 3 except for the support member in the ringseal 10. FIG. 4 does not show a vacuum line 14. However, it will beappreciated that a vacuum line may be provided also in this embodiment.The support member 13 comprises an elastic wire, in particular made of ashape memory material, such as Nitinol. The wire is shown schematicallyin FIG. 4 . FIGS. 6 a and 6 b show different examples for an elasticwire in a cross-sectional view perpendicular to a longitudinal axis ofthe pumping device 2. In order to expand the ring seal 10, the wire isadvanced into the interior of the ring seal 10, e.g. from a lumen thatextends along the catheter 100 into the pumping device 2 and thatstraightens the wire. The wire will assume its predetermined curvedshape once advanced into the ring seal 10. The curved shape may be e.g.helical as shown in FIG. 6 a or otherwise curved as shown exemplarily inFIG. 6 b . The wire acts on the flexible membrane 11 from the interiorof the ring seal 10 and, thus, expands the ring seal 10. In order tocollapse the ring seal 10, the wire can be retracted from the ring seal10 as shown in FIG. 5 . The wire is configured to allow the ring seal 10to collapse when a predetermined minimum pressure acts on the ring seal10, or in other words configured to support the ring seal 10 towithstand a pressure difference only up to a predetermined pressuredifference.

In another embodiment, shown in FIG. 7 , the ring seal 10 comprises aflexible shield 16 extending from a body portion of the ring seal 10.The shield 16 is disposed on a circumference of the ring seal 10 and isconfigured to contact the inner wall of the vessel V when the ring seal10 is in the expanded configuration as shown in FIG. 7 . The shield 16may comprise a membrane and may be relatively flimsy to protect thevessel wall and to improve sealing against the vessel wall. Channels 17may be provided as a stiffening structure that may be filled with afluid to stiffen the shield 16. In order to soften the shield 16, thefluid may be removed from the channels 17. As shown in FIG. 8 , theshield 16 collapses together with the ring seal 10 in the collapsedconfiguration. As in the previous embodiments, the ring seal 10including the shield 16 is configured to collapse when a predeterminedminimum pressure difference between the proximal portion of thepulmonary artery PA and the distal portion of the pulmonary artery PAacts on the ring seal 10 in order to avoid a too high pressure increasein the pulmonary artery PA.

The invention claimed is:
 1. An intravascular blood pump forpercutaneous insertion into a patient's blood vessel, comprising: acatheter, a pumping device attached to the catheter, the pumping devicehaving a blood flow inlet, a blood flow outlet and a rotor so as tocause blood to flow from the blood flow inlet to the blood flow outlet,a ring seal disposed on the pumping device between the blood flow inletand the blood flow outlet, the ring seal configured to assume acollapsed configuration and an expanded configuration and configured tocontact and seal against an inner wall of the patient's blood vesselwhen inserted therein in the expanded configuration so as to separate aproximal area of the patient's blood vessel from a distal area of thepatient's blood vessel, and a support member disposed inside the ringseal in order to support the ring seal from inside the ring seal,wherein the support member is configured to collapse at least partiallywhen a predetermined pressure difference during operation of theintravascular blood pump between the proximal area of the patient'sblood vessel and the distal area of the patient's blood vessel acts onthe ring seal, wherein the support member withstands a pressuredifference during operation of the intravascular blood pump between theproximal area of the patient's blood vessel and the distal area of thepatient's blood vessel of up to 100 mmHg before it collapses.
 2. Theintravascular blood pump of claim 1, wherein the support member isconfigured to withstand a pressure difference during operation of theintravascular blood pump between the proximal area of the patient'sblood vessel and the distal area of the patient's blood vessel of up to20 mmHg before it collapses.
 3. The intravascular blood pump of claim 1,wherein the support member is configured to withstand a pressuredifference during operation of the intravascular blood pump between theproximal area of the patient's blood vessel and the distal area of thepatient's blood vessel from about 5 mmHg to about 35 mmHg.
 4. Theintravascular blood pump of claim 1, wherein the ring seal comprises aflexible membrane.
 5. The intravascular blood pump of claim 4, whereinthe ring seal forms a balloon having an inflation port that allows fluidto be supplied to and to be removed from the balloon.
 6. Theintravascular blood pump of claim 5, wherein the inflation port isconnected to a fluid line so as to allow to inflate the balloon bysupplying fluid to the balloon and to deflate the balloon by removingfluid from the balloon.
 7. The intravascular blood pump of claim 1,wherein the support member is at least partially compressible.
 8. Theintravascular blood pump of claim 1, wherein the support member isbiased to the expanded configuration.
 9. The intravascular blood pump ofclaim 1, wherein the support member comprises a foam or sponge.
 10. Theintravascular blood pump of claim 1, wherein the support membercomprises at least one elastic wire.
 11. The intravascular blood pump ofclaim 10, wherein the at least one elastic wire is made of a shapememory material.
 12. The intravascular blood pump of claim 11, whereinthe shape memory material is Nitinol.
 13. The intravascular blood pumpof claim 1, wherein an outer diameter of the ring seal in the expandedconfiguration is from about 1 cm to about 2.5 cm.
 14. The intravascularblood pump of claim 1, wherein the ring seal comprises a flexible shieldextending from an outer circumference of the ring seal, the flexibleshield configured to contact the inner wall of the patient's bloodvessel when the catheter is inserted in the patient's blood vessel andthe ring seal is in the expanded configuration.
 15. The intravascularblood pump of claim 14, wherein the flexible shield has a proximal endattached to the ring seal and a free distal end configured to contactthe inner wall of the patient's blood vessel.
 16. The intravascularblood pump of claim 14, wherein the flexible shield comprises astiffening structure having at least one fluid receiving channelconfigured to be inflated by receiving a fluid in order to stiffen theflexible shield and to be deflated by removing the fluid in order tosoften the flexible shield.
 17. The intravascular blood pump of claim 1,configured to be inserted into a pulmonary artery.
 18. The intravascularblood pump of claim 1, wherein the support member is configured towithstand a pressure difference during operation of the intravascularblood pump between the proximal area of the patient's blood vessel andthe distal area of the patient's blood vessel from about 7 mmHg to about30 mmHg.